The measuring of temperatures for monitoring and controlling purposes in the most varied applications is effected, for example, using ceramic hot conductor thermistor elements (—“negative temperature coefficient thermistor” or “NTC thermistor”), silicon temperature sensors (for example what are known as “KTY temperature sensors”), platinum temperature sensors (—“platinum resistance temperature detector” or “PRTD”) or thermo elements (—“thermocouple” or “TC”). Ceramic sensor elements are usually provided with a coating produced from a polymer or a glass for sufficient mechanical stability, for protection against external influences and for avoiding corrosion as a result of aggressive media, and for avoiding temperature-related material changes as a result of the gas atmosphere in an NTC material or in an electrode. The maximum operating temperatures of such sensor elements are limited to approximately 200° C. in the event of a polymer covering and to approximately 500° C. in the event of a glass covering.
However, it is not readily possible to use the described sensor elements permanently for measuring very high temperatures and/or in particularly aggressive media. Nevertheless, in order to be able to plan for use in aggressive media, the sensor elements are often built into a housing of plastics material or high-grade steel. In addition, casting materials are very frequently used for producing a thermal contact with the element. A great disadvantage of the systems constructed in this manner is their delayed response time on account of the additional structural-related thermal transfers and the low thermal conduction of the materials used. A particular disadvantage of temperature probes with a polymer or glass covering is the geometry of the temperature probe which fluctuates greatly and cannot be closely toleranced. Consequently, said temperature probes are not suitable for standard installations.